For the pie: Melt the butter in large sauteuse or saute pan over medium-high heat.,Add the onion and sweat until they are soft and translucent.,Add the peas and carrots to the pan, stir to combine and heat through, then remove the mixture to a bowl and set aside.,Preheat your oven to 350 degrees F.,Return the pan to the heat, add the meat, and brown (do not drain grease).,Once meat is browned, sprinkle the flour over the meat and stir well to combine.,Add the garlic, broth, herbs, salt and pepper to the pan and mix well.,Bring the mixture to a slight boil and cook until the liquid is reduced by about half.,Add the vegetable mixture to the pan, stir and remove from the heat.,Spread the meat and vegetable mixture evenly in the bottom of a greased large oval or 9 x 13 baking dish.,Spread the prepared mashed potatoes evenly over the meat.,Bake for 30 minutes then remove the pie from the oven and set aside.,While its baking, make the gravy: Return the pan to the heat at medium-high.,Sweat the shallots over medium heat until they are translucent, then remove to a bowl and set aside.,______,When the butter is foaming, add the flour and whisk very well to make a roux.,Continue cooking, whisking constantly, until the roux starts to develop a nutty aroma (about two minutes).,Reduce the heat to medium and add the porter and broth.,Continue whisking until the mixture is smooth with no lumps.,Return the shallots to the pan and add the remaining gravy ingredients.,Bring the mixture just to a light boil.,Reduce the heat to medium-low and cook another five minutes.,Remove the gravy to a bowl.,Serve the pie with a good amount of the gravy spooned on top and enjoy!